5-EPI-penicillins

ABSTRACT

5-Epi-penicillin esters and acids, the acids being useful as inhibitors of Beta -lactamase type enzymes, a process for preparing such compounds by reacting an ester of a 2-halo- Alpha -(1&#39;&#39;-halothio-1&#39;&#39;-methylethyl)-4-oxo-3-imido-1-azetidineacetate with (a) zinc in acid or (b) stannous chloride in an organic liquid medium at 0* to 100*C., and some new 2-halo- Alpha -(1&#39;&#39;cyanodithia- or 1&#39;&#39;-mercapto-1&#39;&#39;-methylethyl)-4-oxo-3-imido-2azetidineacetate which are useful as intermediates in preparing the 5-epi-penicillins.

United States Patent 1191 Kukolja 1 S-EPl-PENICILLlNS [75] inventor:

[73] Assignee: Eli Lilly and Company, lndianapolis,

Ind.

[22] Filed: July 15, 1971 [21] Appl. No.: 165,758

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 148,129, May 28,

1971 abandoned.

Stjepan Kukolja, Indianapolis, Ind.

[52] U.S. Cl 260/306] C; 260/239.l; 424/271;

[ 51 July 29,1975

Primary Examiner-Nicholas S. Rizzo Attorney, Agent, or Firm-William C. Martens. Jr.; Everet F. Smith [57] ABSTRACT S-Epi-penicillin esters and acids, the acids being useful as inhibitors of B-Iactamase type enzymes, a process for preparing such compounds by reacting an ester of a 2-halo-a-( 1 -hal0thio-l methylethyl )-4-oxo-3- imido-l-azetidineacetate with (a) zinc in acid or (b) stannous chloride in an organic liquid medium at 0 to 100C, and some new 2-halo-a-( l '-cyanodithia or 1 '-mercaptol '-rnethylethyl)-4-oxo-3-imido-2- azetidineacetate which are useful as intermediates in preparing the fi-epi-penicillins.

10 Claims, N0 Drawings S-EPl-PENICILLINS CROSS REFERENCE This application is a continuation-in-part of my application Ser. No. l48,l29, filed May 28, 1971 and abandoned after the filing of this application.

INTRODUCTION BACKGROUND OF THE INVENTION In my prior co-pending application Ser. No. 148,129, filed May 28, i971, I described and claimed some new 2-halo-a-( l '-sulfenylhalo-l -methylethyl)-4-oxo-l azetidineacetate ester and acid compounds of the formula COORe O\ CH3 cm I R1N' \Y with an electrophilic reagent in the form ofa source of 50 positive halogen in an aprotic solvent.

SUMMARY OF THE INVENTION N This invention provides new 5-epiapenicillin esters and acids. The acidsare useful as inhibitors of B-lacta- :mase enzymes e.g. in fermentation media. The new-5 epi-penicillins are prepared by reacting a 2-halo-a-( l halothio, mercapto, or -SSCN-l'-methylethyl)-4-oxo- 3-imido-l-azetidineacetate ester with (a) zinc in acidv or (b) stannous chloride in an organic liquid medium at to 100C. The -epi-penicillin acids are prepared from the esters by deesterification with acid orby hydrogenation procedures. This invention also provides some new 2-halo-a-(l'-cyanodithioor l'-mercaptol -methylethyl)-4-oxo-3-imido-l-azetidineacetate esters and acids which are useful as intermediates in preparing the new S-epi-penicillins of this invention.

DETAILED DESCRIPTION OF-.THE INVENTION One aspect of this invention provides new 5-epipenicillin esters and acids of the formula cooas,

wherein R taken alone, denotes an acyl group of the formula Q is hydrogen, chloro, bromo, C, -C alkyl, C -C alkoxy, nitro or cyano;

20 where R is 30 W is oxygen, or a carbon to carbonbond; and

misanintegerof0to2; R taken alone, is defined as R, above, or is i R4 v 35 I V c c -co- Ru ii ll i taken together with the nitrogen to which they are bonded to form a cyclic imide group or radical having from 3 to about 20 carbon atoms; and R is hydrogen or the residue of an ester group which is removable by acid or hydrogenation procedures. A preferred subgroup of these new compounds are those wherein R, and R are taken together with the nitrogen to which they are bonded to form a succinimido or phthalimido group or bis acylimide group and R is hydrogen or a C to C -alkyl, p-nitrobenzyl, p-methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2-trichloroethyl, phenacyl, or p-halophenacyl where halo denotes chlorine or bromine.

Examples of compounds of this invention include:

p-Nitrobenzyl 6-[N- (phenoxyacetyl)phenylacetamido]-5-epipencillanate Benzhydryl 6-[N-(3',4'- dichlorophenylacetyl)phenoxyacetamido]-5-epipenicillanate tert-Butyl 6-[N-(4'- methoxyphenylacetyl)phenoxyacetamido]-5-epipenicillanate p-Methoxybenzyl 6-[N-( 3 methylphenylacetyl)phenylpropionamido]-5-epipenicillanate,

where each of R and R is hydrogen or halogen (fluorine, chlorine, bromine, or iodine); R and R are Phthalimidomethyl 6 [N-('- nitrophenoxyacetyl )phenoxyacetatnido] -epipenicillanate, v

Succinimidomethyl 6 [N (3' cyanophenylacetyl)phenylacetamidolS-epipenicillanate 2,2,2-Trichloroethyl penicillanate,

p-Nitrobenzyl I 6-[ N- (phenoxyacetyl)phenylacetamido]-5-epi-penicillanate,

Benzhydryl 6-3-nitrophthalimido-5-epi-penicillanate,

tert-Butyl 6-phthalimido-5-epi-penicillanate,

2,2,2-Trichloroethyl 6-succinimido-5-epipenicillanate, I

Benzyl 6-bis p henylacetylimido-5-epi-penicillanate,

p-Nitrobenzyl 6-(methylmalonimido)-5-epipenicillanate,

Phenacyl 6-glutarimido-5-epi-penicillanate,

2,2,2-Trichloroethyl N-( 3 -phenyl-5 '-methyl-4- isoxazolyl)phenylacetylamido-S-epi-penicillanate, p-Methoxybenzyl 6-(4'wchlorophthalimido)-5-epipenicillanate,

Phthalimidomethyl penicillanate,

Methyl 6-diglycolimido-S-epi-penicillanate,

Benzhydryl 6-phthalimido-5Pepi-penicillanate, I

and the corresponding acids, which are obtained after deesterificationby treatment of the esters with acids such as trifluoroacetic acid, hydrochloric acid, zinc in formic, acetic or hydrochloric acid, or by hydrogenating the ester with hydrogen in the presence of a palladium or rhodium metal or compound, in suspension or on a carrier such as barium sulfate, carbon, alumina or the like:

The configuration of these new S-epi-penicillin compounds can be compared to that of natural penicillins by the formulas Ill and IV which follow depicting the trans-arrangement of protons in the azetidinone ring, and consequently the trans or S-epifusion of the azetidinone and thiazolidine rings ofa S-epi-penicillin in formula III 6-diglycolimido 5 -epi- 6-succinimido-5-epi- COORa l I O N,CH /CHa L III E: a s Ha R1 4 N H trans (or S-epih wherein R,, R and R are as defined above, and

RiCONH COORa l o Ha IV 'l 4s CH3 R1 N c i (or natural) The cyclic imide group or radical defined by R, and R being taken together with the nitrogen to which they are bonded can be formed by reacting the 6-amino group of 6-aminopenicillanic acid (6-APA) or a 6- aminopenicillin ester with a C to C -hydrocarbon dibasic acid or an anhydride or other reactive variant thereof, followed by reacting the resulting derivative with a C to C -alkyl haloformate, e.g., ethyl chloroformate, in the presence of an organic base. Cyclic imides can be made from succinic, glutaric, diglycolic, phthalic acids or anhydrides, as well as from cyclohexanjedicarboxylic, 3-cyclohexenel ,Z-dicarboxylic, halogen substituted dicarboxylic acids or anhydrides such as 4,5-dichlorophthalic, tetraiodophthalic, pbromophthalic, as well as related epoxybridged compounds such as 2,5-epoxycyclohexane-l ,2- dicarboxylic, and 2,5-epoxy-3-cyclohexenel ,2- dicarboxylic acids and anhydrides, and compounds of similar reactivities to form cyclic imides. Additional examples of cyclic anhydrides of the type defined are found in the prior art such as in the Journal of Organic Chemistry, Volume 26, pp. 3365-3367 (September, l96l). 6-Phthalimido penicillanic acid was prepared starting with 6-APA and N-carboethoxyphthalimide according to the procedure of Y. G. Perron et al., Journal of Medicinal Chemistry Vol. 5, (1962), p 1016.

The acyclic imide group or radical defined by R and R being acyl groups can be formed by reacting the imidoyl chloride of penicillin esters (V) with an alkali metal salts (sodium and potassium being the most practical) of acids as described in the prior art such as in Netherlands Patent 7,005,198 and Belgian Patent 738,ll0. These reactions can be illustrated with the following formulas:

Continued RzCOOM V COORa ,CHa

R1 CO-N l RzCO The new S-epi-penicillin esters are useful as intermediates for preparing compounds where R; is hydrogen, or a salt thereof. The most common salt would be sodium, potassium, ammonium, tris(C, to C -alkyl) amine salts. The new S-epi-penicillin acids are useful as inhibitors of ,B-lactamase type enzymes in fermentation media. For example, the compound 6-phthalimido-5- epi-penicillanic acid was found to inhibit over one-half of the cephalosporinase enzyme in an agar plate test in which the bi'oactivit y of cephalosporin C against Salmonella sp. was measures. Similar inhibition of B-lactamase was found bi 'oassay methods using cephaloridine as the antibiotic and B. subtilis, K. pneumonia and Mycobacterium aviurrt as the test microorganisms.

According to theiprocess of this invention the new S-epi-penicillin ester or acid 11] is prepared by treating or reacting a compound of formula I COORs CH3 SH polarity of the solvent or reaction mixture is increased the yield or percentage of the cis (natural) penicillin (ll) [and the l-mercapto intermediate (IV)] is correspondingly enhanced. Thus this invention provides a method for obtaining substantially the S-epi-penicillin (Ill). if that is the desired product, in which case one COORs CHa CHa COORa IIII|H III (trans or S-epi) COORa I IS II (cis or natural) which intermediate cyclizes to a mixture of the cisand transisomers of the imido penicillin ester or acid, the proportions of each depending upon the protic state of the reaction medium.

The 2-halo-a-( l '-halothiol -methylethyl)- 4-oxo-3- imido-l-azetidineacetate ester starting materials can be prepared by treating a 6-imido-penicillanate ester with an electrophilic reagent which serves as a source of positive halogen to effect selective cleavage or opening of the thiazolidine ring between the S and the carbon atom in the S-positionliof the penicillin. The electrophilic cleavage of the thiazolidine ring results in the formation of a mixture ofcisandtrans-isomers of the hydrogen on the 2i- 'c arbon atoms of the resulting 2- azetid inone ring ofithe azetidin'e acetate.

The electrophilic reagent is preferably formed of an electrophilic component X, a source of positive halogen. and a nucleophilic component Y. As used herein. the term source of positive halogen" is intended to refer to and include any source of X wherein X, is chlorine or bromine. A wide variety of halogenating agents are known to those skilled in the art as supplying positive halogen and can be used to prepare the starting materials. Examples of halogenating agents which can be used include the elemental halogens such as chlorine and bromine, sulfuryl chloride, sulfuryl bromide, N-halogeno amides and imides such as N- chlorosuccinimide, N-bromosuccinimide, N,N- dibromohydantoins, and organic hypohalide and particularly the alkanoyl hypohalides such as acetyl hypochlorite, butyryl hypochlorite, acetyl hypobromite, propionyl hypobromite, butyryl hypobromite, and the like. In addition, use can be made of mixed halogens such as BrCl, C11, Br], and the like. As can be appreciated by those skilled in the art, the use of such mixed halogens provides a product containing mixed halogens. The reaction between the penicillin ester and the electrophilic reagent is preferably carried out in an aprotic solvent such as tetrahydrofuran, dioxane, aliphatic and aromatic hydrocarbons and halogenated hydrocarbons such as benzene, toluene, dichlorobenzene, methylene chloride, chloroform, bromoform, carbon tetrachloride, carbon tetrabromide and the like. The temperature of this reaction can vary over a wide range depending upon the nature of the side chain of the penicillin starting material. With 6-bis(acyl)imido side chains temperatures of from 76C. to C., and with 6-cyc1oimido side chains the temperature can vary from -76C. to 80C.

The cyclization reaction of the process of this invention favors the formation of the S-epi-penicillin when an aprotic solvent such as tetrahydrofuran or dioxane and anhydrous conditions are used. Examples of aprotic solvents which can be used are given above where the description of the preparation of the starting materials is given. The ratio of the natural penicillin configuration in the product increases as the protic condition of the reaction mixture is increased. These conditions are enhanced by small amounts of water introduced with reactants or solvents.

As part of this invention new compounds of the for mula COORa 0 C CH:

CH 1 5 R1 N x z furan at room temperature for about 2 hours. This product (1V) can then be cyclized to the S-epipenicillin compound of this invention with anhydrous stannous or zinc chloride.

The 2-ha1o-a-( 1-cyanodithio-1'-methy1ethy1)-4- oxo-3-imido-1-azetidineacetate compounds (where Z is -SC N) are obtained by reacting an alkali metal thiocyanate such as sodium or potassium thiocyanate with the 2-ha1o-a-(1'-ha1othio-1'-methy1ethyl)-4-oxo-3- imido-l-azetidineacetate in an aprotic solvent at 0 to 50C., preferably at room temperature. These cyanodithio compounds can be used in the process for preparing the S-epi-penicillins of this invention as described above.

The invention is further illustrated by the following detailed examples, which are not intended to be limiting of the scope of the invention.

EXAMPLE l Preparation of Methyl 6-phthalimido-5-epipenicillanate I A mixture of 3.6 g. of trans methyl 2-chloro-a-(1'- chlorothio- 1 -methylethyl )-4-oxo-3-phthalimido- 1 azetidineacetate and 2.5 g. of stannous chloride dihydrate and 100 ml. of dioxane was heated on a steam bath for 1 hour. The residue obtained after evaporation of the solvent was dissolved in chloroform, the solution washed twice with water and dried. The crude product, 2.2 g., was a mixture of trans (S-epi) and cis penicillins in a ratio of about 5:1 transzcis. It was recrystallized from methyl ethyl ketone-cyclohexane; 670 mg. of colorless prisms of methyl 6-phtha1imido-5-epipenicillanate were collected. A second crop gave 420 mg. Analytical sample melted at 174175C.; [01] l92 (CHCls); nmr (CDCl (s, 3H), 102 (s, 31-1), 231 (s, 3H), 234 (s, 1H), 327 (d, 1H), J 2.0 Hz), 334 (d, 1H, J 2.0 Hz), and 471 cps (m, 4 ArH); ir (Cl-1Cl 1795 (B-lactam CO); 1785 and 1733 (phthalimido CO), and 1752 cm (ester CO).

Anal. calc. for C H N Q S: C, 56.67; H, 4.47; N, 7.78; O, 22.20; S, 8.90. Found: C, 56.68; H, 4.60; N, 8.02; O, 21.92; S, 9.05 percent.

EXAMPLE 2 Preparation of 2,2,2'Trichloroethyl 6-phthalimido-5- epi-penicillanate A mixture of 2.74 g. of 2,2,2-trichloroethyl 2-chloroa-( 1 -chlorothio-1-methylethy1)-4-oxo-3-phthalimidol-azetidineacetate, 1.24 g. of stannous chloride dihydrate and 50 ml. of dioxane was heated on a steam-bath for 1 hour. The solvent was evaporated, the residue dissolved in 50 ml. of chloroform, and the solution washed with 10 ml. of 1 N HCl, 25 ml. of Water, 25 ml. of sat. NaHCO 15 ml. of water, dried and evaporated to give 1.75 g. (74%) of crude product. The nmr spectrum showed the product to be a mixture of trans (S-epi) and cis penicillins in a ratio ca. 7:1 transzcis. The neutral material was chromatographed on 28 g. of silica gel using 250 ml. of benzene and 500 ml. of a mixture of benzene-ethyl acetate (95:5) as eluting solvent. Fractions containing 20 ml. were collected in 17 minute intervals. Fractions 17-30, 1.38 g., contained 2,2,2- trichloroethyl 6-phthalimido-S-epi-penicillanate, [oz] 127.5, (CHCl nmr (CDC1 96 (s, 3H) (s, 3H), 242.5 (s, 1H), 291.5 (s, 2H), 329 (d, 11-1, .1 2.0 Hz), 335 (d, 1H, J 2.0 Hz), and 470 cps (m, 4 Arl-l); ir (Cl-1C1) 1796 (B-lactam CO), 1764 and 1735 (phthalimido CO), and 1735 cm (ester CO).

In a similar experiment, cis penicillin was first isolated by dissolving the crude product in ethyl ether. The crystals, m.p. 23537C., of 2,2,2-trichloroethyl 6-phthalimidopenicillanate were filtered, the filtrate evaporated and the crude ester of corresponding S-epipenicillin was purified by chromatography over silica gel.

EXAMPLE 3 A. Preparation of Benzhydryl 6- phthalimidopenicillanate To a solution of 3.44 g. (0.01 mole) of 6- phthalimidopenicillanic acid in 30 ml. of ethyl acetate 2.33 g. (0.012 mole) of diphenyldiazomethane was added with stirring. After 20 minutes the purple color of unreacted diphenyldiazomethane was discharged with cone HCl and the solution washed with dilute NaHCO and H 0, dried, and evaporated to yield 4.42 g. of ester. This crystallized from a mixture of 30 ml. of ethanol and 15 ml. of acetone to give colorless silky needles, mp l61163C.; [01],, +230.6 (CHCl nmr (CDCl 79 (s, 3H), 110 (s, 3H), 288 (s, H), 338 (d, 1H, J =4 Hz), 343 (d, 1H,J=4 Hz), 421 (s, 1H), 443 (m, 10 ArH), and 469 cps (m, 4 ArH); ir (CHCl) 1800 (B-lactam CO), 1785 and 1735 (phthalimido CO), 1750 cm (ester CO).

Anal. calc. for C H N O S: C, 67.95; H, 4.72; N, 5.47; S, 6.26; O, 15.61. Found: C, 68.14; H, 4.74; N, 5.55; S, 6.19; O, 15.47%.

B. Benzhydryl 2-chloro-a-(1'-chlorothio-1'- methylethyl)-4-oxo3-phthalimido-l-azetidineacetate A solution of 17.5 g. of benzhydryl 6- phthalimidopenicillanate in 50 ml. of methylene chloride was cooled in an ice-bath and 34 ml. of 1M chlorine solution in carbon tetrachloride was added and stirred for 30 minutes. The solvent was evaporated and the residue dried in vacuo. The title compound was obtained almost in quantitative yield; nmr (CDCI 100 (s, 3H), 104 (s, 3H),288(s,1H), 328 (d, J 1.5 Hz, IH), 360 (d, J =1.5 Hz, IH), 422 (s, H), 443 (m, 10 ArH), and 469 cps (d, 4 ArH).

Anal. calc. for C H Cl N O S: C, 59.70; H, 4.15; C], 12.15; N, 4.80; O, 13.71; S, 5.30. Found: C, 59.91; H, 4.28; Cl, 12.30; N, 4.59; O, 13.54; S, 5.50 percent. C. Preparation of Benzhydryl 6-phthalimido-5-epipenicillanate A solution of 29.15 g. (0.05 mole) of benzhydryl 2- chloro-a-( l -chlorothio-l '-methylethyl)-4-oxo-3- phthalimido-l-azetidineacetate and 9.5 g. (0.05 mole) of stannous chloride in 291 ml. of tetrahydrofuran was stirred at room temperature for 2 hours; the solvent was evaporated, the residue dissolved in ethyl acetate, washed twice with water, dried and the solvent evaporated to give a crude product which was chromatographed over silica gel using a linear gradient mixture of benzene-ethyl acetate. Fractions containing ml. were collected at 17 minute intervals. Fractions 77-101, 6.0 g. of colorless solid, constituted benzhydryl 6-phthalimido-S-epi-penicillanate; [01],, 75 (CHCl nmr (CDCl 76 (s, 3H), 99 (s, 3H), 240 (s, IH), 328 (d, 1H, J 2.0 Hz), 335 (d, 1H, J 2.0 Hz), 424 (s, l H), 446 (m, 10 ArH), and 470 cps (m, 4 ArH); irv (CHCl) 1796 (B-lactam CO), 1785 and 1735 (phthalimido CO), and l745cm (ester CO).

Anal. Calc. for C H N O S: .C, 67.95; H, 4.72; N,

5.47; S, 6.26; O, 15.61. Found: C, 68.03; H, 5.00; N, 5.38; S, 6.48; O, 15.82%.

EXAMPLE 4 Preparation of 6-Phthalimido-5-epi-penicillanic acid A mixture of 620 mg. of benzhydryl 6-phthalimido-5- epi-penicillariate, 0.4 ml. of anisole and 1.6 ml. of trifluoroacetic acid was stirred in an ice-bath for 15 minutes, and then evaporated in vacuo. The residue was dissolved in ethyl acetate, the acid extracted with dilute NaHCO the aqueous solution separated and acidified with cone HCl, the desired acid re-extracted with ethyl acetate, the extract dried and evaporated. The title acid, 250 mg., was isolated as a colorless amorphous solid: [01],, l03.5 (CHCl nmr (CDCl 94 (s, 3H), 103 (s, 3H), 238.5 (s, 1H), 324.5 (d, 1H, J 2.0 Hz), 330.5 (d, 1H, J= 2.0 Hz), and 472 cps (m. 4 ArH); ir (CHCl) 1795 (B-lactam CO), 1782 and 1735 cm (phthalimido CO). A

Anal. Calc. for C H N O S: C, 55.48; H, 4.07; N, 8.09; O, 23.10; S, 9.26. Found: C, 55.29; H, 4.25; N, 7.97; O, 23.40; S, 9.47%.

EXAMPLE 5 The Reaction i' of trans methyl 2-chloro-a-( l chlorothiol"-methylethyl 4-oxo-3-phthalimidol i azetidineacetate with acetic acid and zinc To a solution of 8.6 g. (0.02 mole) of trans methyl'2- chloro 1 -chlorothio-l '-methylethyl)-4'oxo-3- phthalimido-l-azetidineacetate in 50 ml. of toluene and 25 m1. of acetic acid, 3.6 g. of zinc dust was slowly added for 8 minutes. After stirring at room temperature for 1 hour, the solvent was evaporated, the residue dis solved in m1; of ethyl acetate and 30 ml. of a saturated solution ofi'sodium bicarbonate, theorganic layer separated, washed with 30 ml. of water, dried (Na S0 and the solvent evaporated to give 8.15 g. of crude product. This was chromatographed over silica gel using a linear gradient mixture of benzene andethylacetate. Fractions containing 21.5 ml. were collected at 20 minute intervals. Fractions 35-70, 1.3 g., were a mixture of four compounds; this material on recrystallization from 3 ml. of acetone afforded 290 mg. of colorless prisms ofi methyl 6-phthalimidopenicillanate, mp 171-173C.; nmr (CDCl;,) 9. (s, 3H), (s, 3H), 228 (s, 3H), 281 (s, 111-1), 334 (d, 1H, J 4.0 Hz), 342 (d, 1H, J 4.0 Hz), and 470 cps (m, 4 ArH).

The filtrate was evaporated and 200 mg. of the residue was chromatographed on a preparative thin layer chromatography silica gel plate using a mixture of cyclohexane and fnethyl ethyl ketone (4:1). The major stripe was extracted with chloroform and acetone giving mg. of colorless product which was recrystallized from 2.5 ml. of a v/v mixture of cyclohexane and methyl ethyl ketone (4:1) to give colorless rosettes, mp 174-175C., of methyl 6-phthalimido-5-epipenicillanate", nmr (CDCl 90 (s, 3H), 102 (s, 3H), 231 (s, 3H), 234.5 (s, IH), 327 (d, 1H, J 2.0 Hz), 334 (s, 1H, J =2.0 Hz), and 471 cps (m, 4 ArH). The mass spectrum showed a molecular ion at m/e 360.

Anal. calc. for C H N O S: C, 56.67; H, 4.47; N, 7.78; S, 8.90. Found: C, 56.42; H, 4.54; N, 7.92; S, 8.70%.

The remaining two compounds were identified as cis and trans isomers of methyl 2-acetoxy-a-( l-mercapto- 2'-methylpropyl)-4-oxo-3-phthalimidolv azetidineacetate.

Fractions 85115, 2.83 g. of colorless amorphous solid, were a mixture of trans and cis (6:1) isomers of corresponding disulfides. The isomers were separated by using preparative thin layer chromatography silica plates: trans dimethyl 3,3-dithiobis[3-methyl-2-(4'- acetoxy-3 '-phthalimido 1 '-azetidin2-onyl )butyrate] was an amorphous solid: nmr (CDCI 100 (s, 12H), 128 (s, 6H), 230 (s, 6H), 274 (s, 2H), 317 (d, 2H, .1 1.5 Hz), 400 (d, 2H, J 1.5 Hz) and 472 cps (m, ArH); ir (CHCl 1800, 1789, 1757, and 1735 cm.

Anal. calc. for C H ,,N O S C, 54.41; H, 4.57; N, 6.68; S, 7.65. Found: C, 54.25; H, 4.69; N, 6.38; S,

EXAMPLE 6 The reaction of transmethyl 2-chloro-a-( 1 -chlorothio- 1-methylethyl)-4-oxo-3-phtha1imido- 1 azetidineacetate with sodium thiocyanate A solution of4.31 g. (0.01 mole) of methyl 2-chloroa-(1-ch1orothio-l'-methylethy1) -4-oxo-3-phthalimidol-azetidineacetate in 50 ml. of benzene was mixed with a solution of 0.9 g. of sodium thiocyanate, the mixture stirred at room temperature for 15 minutes, washed with water, dried and the solvent evaporated. The residue was recrystallized from methylene chloridepetroleum ether, and colorless crystals of methyl 2- chloro-a-(1-cyanodithia-l'-methylethyl)-4-oxo-3- phthalimido-l-azetidineacetate melted at 1 l7l 19C.; nmr (CDCl 109 (s, 6H), 232 (s, 3H), 276 (s, 1H), 333 (d, 1H,.] 1.5 Hz), 364 (d, 1H, .1 =1.5 Hz), and 472 cps (m, 4 ArH); ir (CHCl 2155, 1800 (,B-lactam CO), 1790, 1732 (phthalimido CO), and 1752 cm (ester CO).

Anal. calc. for c,,.H,,clN,o ,s C, 47.61; H, 3.55; Cl, 7.81; N, 9.26; S, 14.13. Found: C, 47.40; H, 3.56; Cl, 8.03; N, 9.43; S, 14.03%.

EXAMPLE 7 The reaction of methyl 2-ch1oro-a-(1-cyanodithio-1- methylethyl )-4-oxo-3-phthalimidol -azetidineacetate with acetic acid and zinc To a solution of 2.7 g. of methy1-2-ch1oro-a-(1- cyanodithio-l -methylethyl)-4-oxo-3-phthalimido-1- azetidineacetate in 40 ml. of acetic acid 2.7 g. of zinc dust was added in 10 minutes; the mixture was stirred at room temperature for 1 hour and filtered. The filtrate was evaporated, the residue dissolved in ethyl acetate, the solution washed with dilute NaHCO and H 0. dried, and evaporated to give 2.3 g. of a viscous oil. Thiswas chromatographed over silica gel using a linear gradient mixture of benzene and ethyl acetate. Fractions containing 20 ml. were collected at 20 minute intervals. Fractions 31-81, 610 mg., contained a mixture of four products; after recrystallization from acetone 120 mg. of colorless prisms, mp 171-173C., of methyl 6-phthalimidopenicillanate were obtained. The filtrate was evaporated and the remaining three compounds were identified as: (a) methyl 6-phthalimido-5-epipenicillanate, (b) cis and (c) trans methyl 2-acetoxy-oz- 1 '-mercapto-l '-methylethy1)-4-oxo-3phthalimido- 1 azetidineacetate.

Fractions 82-86 contained 17 mg. of colorless amorphous solid of trans dimethyl 3,3'-dithiobis[3-methyl- 2-( 4 '-acetoxy-3 -phthalimido- 1 -azetidin-2- onyl)butyrate, nmr (CDCl 100 (s, 12H), 128 (s, 6H),

230 (s, 611), 274 (s, 21-1), 317 (d, 2H, J =1.5 Hz).

(d, 2H, J 1.5 Hz), and 472 cps (m, 8 ArH).

Fractions 87-101, 640 mg., were a mixtureof corre sponding cis and trans disulfides. l

EXAMPLE .8

Methyl 2.-chloro-a-( 1 -mercaptol -methylethyl)-4- oxo-3-plfthalimido-2-azetidineacetate Method A. A mixture of 862 mg. (2 mM) of methyl 2-chloro a-(l '-ch1orothio-1 '-methy1ethy1)-4-oxo-3- phthalimido-l azetidineacetate, 25 ml. of carbon tetrachloride, 10 ml. of'acetic acid, 374mg. (2.2 mM) of potassium iodide and 40 ml. of a 0.1 N solution of sodium thiosulfate is stirred for 35 minutes at room temperature. The organic phase is separated and the aqueous phase is extracted with 35 ml. of carbon tetrachloride. The organic extracts are combined, and the resulting mixture is washed with water, dried and the solvent evaporated. The residue is then chromatographed over 7 silica gel using a mixture of benzene and ethyl acetate (:5) as the eluting solvent. Fractions 3 to 6 are combined, and mg. of a colorless product is obtained by crystallization from 3.0 ml. of acetone with 1 ml. water. The title compound is obtained in the form of colorless needles, mp: 156157C.; ir (KBr) 2578, 1780, 1770,1742, and 1725 cm; nmr (CHCl 99 (s, 3H); 101 (s, 3H); (s, 1H) exchanges with D 0; 230 (5, 31-1); 273 (s, 1H); 336.5 (d, 1H, .1 2 Hz), 387.5 (d, 1H, J 2 Hz), 475 cps (m 4 ArH).

Anal. calc. for C H ClN O S: C, 51.58; H, 4.07; C], 8.96; N, 7.08; S, 8.10. Found: C, 51.35; H, 4.27; Cl, 9.14; N, 7.23; S, 7.98.

Method B. A mixture of 4.31 g. (0.01 mole) of methyl 2-chloro-0z-( l '-chlorothio-l-methylethyl)-4- oxo-3-phthalimido-2-azetidineacetate 2.36 g. (0.0105 mole) of stannous chloride dihydrate in 43 ml. of tetrahydrofuran was stirred at room temperature for 2 hours, and then evaporated to dryness on a ro'tavapor. The residue was dissolved in 43 ml. of ethyl acetate, washed with 20 ml. of water, a solution of NaHCO (420 mg. in 20 m1. of water), and again 20 ml. of water, dried (MgSO the solvent evaporated to give 3.55 g. (90 percent) of the title compound, which was crystallized from aqueous acetone. The colorless needles, mp l5657C., are identical with the product obtained according to the Method A.

EXAMPLE 9 Preparation of Methyl 6-phthalimido-5-epipenicillanate via mercapto compound A mixture of 396 mg. of methyl 2-chloro-a-(l'- mercapto-1 -methy1ethy1)-4-oxo-3-phthalimido2- azetidineacetate and mg. of anhydrous stannous chloride in 10 m1. of tetrahydrofuran was heated on a steam-bath for 1 hour and the solvent evaporated. The residue was dissolved in 15 ml. of ethyl acetate, washed twice in 10 ml. of water, dried (MgSO the solvent evaporated, and a crude product dried in vacuo. The nmr spectrum shows a complete conversion to the title compound. After recrystallization from methyl ethyl ketone and cyclohexane colorless prisms, mp. l7475C., ofi methyl 6-phthalimido-5-epipenicillanate were obtained.

- EXAMPLE 10 Preparation of 2,2,2-Trichloroethyl 6-Succinimido-5- epi-penicillanate A. Preparation of 2,2,2- trichloroethyl 6-(B-carboxy)- propionamido penicillanate A mixture ofj3.84 got the hydrochloride of 2,2,2-

trichloroethyl 6-aminopenicil1anate, 38 ml. of chloroform. 1.0 g. of succinic anhydride and 1.4 ml. of triethylamine is refluxed for 75 minutes, filtered and the filtrate washed with 10 ml. of 1 N solution of hydrochloric acid. twice with water and once with brine, dried and the solvent evaporated. Yield, 1.94 g.; nmr (CDCl 96 (s, 3H), 103 (s, 3H), 160 (s, 4H), 275 (s, 1H), 290 (s, 2H), 339 (q, 1H J =4 Hz), 346 (d, 1H J 4 Hz) and 415 Hz (d, lNH. J 8 Hz). B. Preparation of 2,2,2-trichloroethyl succinimidopenicillanate A mixture of 2.46 g. of 2,2,2-trichloroethyl 6-(13- carboxy)propionamidopenicillanate, 40 ml. of methylene dichloride, 1.4 ml. of triethylamine and 0.5 ml. of ethyl chloroformate is stirred at C. for 1 hour. After that it is washed with water and brine, the solvent evaporated to yield 1.59 g. of the crude product which is chromatographed over 30 g. of silica gel and eluted with benzene and ethyl acetate (90:10). Fractions 11-30 gave 430 mg. of 2,2,2-trichloroethyl 6- succinimidopenicillanate: ir (CHCl 1801, 1775 and 1730 cm"r.nmr(CDCl )96(s.3l-1), l08(s,3H), 168 (s, 4H), 284 (s, IH), 290 (d, J 2 Hz, 2H), 330 (d, J 4 Hz), and 336 Hz (d, J 4 Hz, 1H). C. 2,2,2-Trichloroethyl 2-chloro-a-( l -chlorothio-l methylethyl)-4-oxo-3-succinimido-lazetidineacetate A solution of 4.1 g. of 2,2,2-trichloroethyl 6- succinimidopenicillanate in 41 ml. of methylene chloride was cooled to 50C. and 10 ml. of 1 M chlorine solution in carbon tetrachloride was added and stirred for 45 minutes. The solvent was evaporated and the residue dried on a pump. The title compound was obtained as a mixture of cis and trans isomers in a ratio of ca. 1:5. D. 2,2,2-Trichloroethyl penicillanate A solution of 3.12 g. of 2,2,2-trichloroethyl 2-chloroa-(1-chlorothio-l-methylethyl)-4-oxo-3-succinimidol-azetidineacetate and 1.16 g. of anhydrous stannous chloride in 31 ml. of tetrahydrofurane was stirred at room temperature for 2 hours; the solvent evaporated, the residue dissolved in ethyl acetate, washed twice with water and once with brine, dried (MgSO and the solvent evaporated to give 2.4 g. of a crude product which was chromatographed over 60 g. of silica gel using a linear gradient mixture of benzene ethyl acetate. Fractions containing S-epi-penicillanate were collected and the solvent evaporated giving 700 mg. of pure product; nmr (CDC1 94 (s, 3H), 103 (s, 3H), 164 (s, 4H), 239 (s, IH), 291 (s, 2H), and 325 Hz (s, ZB-lactam H); ir (nujol) 1780, 1755 and 1710 cm.

EXAMPLE 1 1 Preparation of 2,2,2-Trichloroethyl N-(3-phenyl-5- methyl-4-isoxazolyl) benzyl-Sepi-penicillanate A. 2,2,2-Trichloroethyl N-(3-phenyl-5-methyl-4- isoxazolyl)benzyl-penicillanate A suspension of 2.36 g. of phosphorus pentachloride and 2.4 ml. of quinoline was cooled to -l0C. and 4.65 g. of 2,2,2-trichloroethyl added and stirred at 10C. for minutes. A solution was washed with 2.15 g. of sodium bicarbonate in 30 ml. of water, twice with 20 ml. of water and 20 ml. of brine, dried (MgSO the solvent evaporated and the oily product dried in vacuo. The nmr spectrum shows the complete conversion to imido chloride. The oil was dissolved in 70 ml. of dioxane and 3.6 g. of potassium 3-phenyl-5methylisoxazolyl-4-carboxylate was added 6-succinimido-5-epibenzylpenicillanate was and the mixture stirred at 40C. for 4 hours. The solvent was evaporated, the residue dissolved'in 50 ml. of chloroform and 25 ml. of water, the organic layer washed with a solution of sodium bicarbonate, water, 0.1N hydrochloric acid, water and brine. After drying the solvent was evaporated and 4.2 g. of a crude prod uct chromatographed over 100 g. of silica gel using a mixture of benzene and ethyl acetate (95:5). Fractions (22 ml.) 41-91 gave 2.34 g. of 2,2,2-trichloroethyl N- (3-phenyl-5rriethyl-4-isoxazolyl) benzylpenicillanate; nmr (CDCl (s, 3H), 101 (s, 3H), 152 (s, 3H), 229.5 (s, 2H), 275.5 (s, 1H), 285.5 (d,.1= 1.5 Hz, 2H), 292 (d, J=4.0 Hz, 1H), 318 (d, J =4.0 HZ, 1H), 436.5 (m, 5H), and 448 Hz (s, 5H). B. Chlorinolysis of bisacylimide ester A solution of 1.3 g. of the acyclic imide obtained as described under A in 20 ml. of methylene chloride was cooled to -76C. and 2.1 ml. of 1M chlorine solution in carbon tetrachloride was added and stirred for 30 minutes. The solvent was evaporated and the residue dried in vacuo. The crude 2,2,2-trichloroethyl 2- chloro-a-( l -chlorothio-l -methylethyl)-4-oxo-3-[N- (3-phenyl-5methyl-4-isoxazolyl)N- phenylacetyl]imido-lazetidineacetate was ately used in the next step. C. Cyclization to S-epi-penicillanate The 2,2,2-trichloroethyl 2-chloro-oz-( l '-chlorothiol-methylethyl )-4-oxo-3-[ N-( 3-phenyl-5-methyl-4- isoxazolyl)N-phenylacetyl]imido-1azetidineacetate obtained as described above under B was dissolved in 20 ml. of tetrahydrofurane and to a solution 390 mg. of anhydrous stannous chloride was added and stirred at room temperature for 2 hours. The solvent was evaporated, the residue dissolved in ethyl acetate and washed with water, dried and the solvent evaporated to give a crude product which was chromatographed over silica gel using benzene as eluting solvent. The desired 5-epipenicillanate (title compound) was isolated and characterized by spectral data.

EXAMPLE 12 This example illustrates the use of the S-epipenicillanic acid compounds of this invention as an inhibitor of B1actamase type enzymes. For this example the compound 6-phthalimido-S-epi-penicillanic acid was used.

The compound 6-phthalimido-5epi-penicillanic acid was added to medium containing a cephalosporinase enzyme from contaminate bacterium. The reaction medium contained 11.4 millimole of cephalosporin C, 50 millimoles of [tris(hydroxymethyl)aminomethane] buffer pH 8.6, 0.2 ml. of the cephalosporinase enzyme, and either 5.78 millimoles or 2.89 millimoles of 6- phthalimido-Sepi-penicillanic acid. The total volume in each test was 2 ml. The reaction media were heated at 37C. for 5 hours. Samples were taken at various times using 13 mm. discs. These discs were plated on agar seeded with Salmonella sp. The plates were incubated overnight at 38C. Then the percent bioactivity of the cephalosporin C was measured. The results were as follows:

immedipenicillanic acid 15 These results show that there was a substantial inhibition of cephalosporinase enzyme activity. These results show that the compound, 6-phthalimido-5-epipenicillanic acid is useful as an enzyme inhibitor in fermentation media where cephalosporin C is being produced by fermentation methods.

EXAMPLE 13 Preparation of Methyl 6-phthalimido-5-epipenicillanate via mercapto compound with zinc chloride A mixture of 396 mg. of methyl 2-chloro-a-(1- mercapto-l -methylethyl )-4-oxo3-phthalimidol azetidineacetate and 136 mg. of zinc chloride in ml. of tetrahydrofuran was heated on a steambath for l hour and the solvent evaporated. The residue was dissolved in ml. of ethyl acetate, washed twice in 10 ml. of water, dried (MgSO the solvent evaporated, and a crude product dried in vacuo. The nmr spectrum shows a complete conversion to the title compound. After recrystallization from methyl ethyl ketone and cyclohexane colorless prisms, mp. l7475C., of methyl 6-phthalimido-5-epi-penicillanate were obtained.

I claim:

1. A S-epi-penicillin compound of the formula wherein R,, taken alone, denotes an acyl group of the formula where R is O is hydrogen, chloro, bromo, C to C -alkyl, C to C alkyloxy, nitro or cyano, W is oxygen, or a chemical bond; and m is an integer of from O to 2;

R taken alone, is defined as R above, or is 4 cc -00- R5 u u N c CH3 where each of R and R is hydrogen or a halogen (fluorine, chlorine, bromine or iodine);

or R and R are taken together with the nitrogen to which they are bonded to form a succinimido or phthalimido group, and R is hydrogen, C to C alkyl, p-nitrobenzyl, p-methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2-trichloroethyl, trimethylsilyl, phenacyl, or p-halophenacyl where halo denotes chlorine or bromine.

2. A compound as defined in claim 1 wherein R and R are taken together with the nitrogen to which they are bonded to complete a succinimido or phthalimido group, and R is a C, to C -alkyl, p-nitrobenzyl. p-

methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2- trichloroethyl, trimethylsilyl, phenacyl, or pwherein R taken alone, denotes an acyl group of the formula Q is hydrogen, chloro, bromo, C -C alkyl, C -C alkoxy, nitro or cyano;

W is oxygen, or a carbon to carbon bond; and

m is an integer of O to 2;

R taken alone, is defined as R, above, or is where R is where each of R and R is hydrogen or halogen or wherein R and R taken together with the nitrogen to which they are bonded complete a succinimido Or phthalimido group, R is hydrogen, C, to C -alkyl, p-

nitrobenzyl, p-methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2- trichloroethyl, trimethylsilyl, phenacyl, or phalophenacyl where halo denotes chlorine or bromine, X is chlorine or bromine, and Y is chlorine, bromine, hydrogen or -SCN with a reagent selected from the group consisting of a. zinc in acetic acid;

b. stannous chloride in a liquid organic medium at a temperature of from about 0 to C, or c. when Y is hydrogen, zinc chloride in a liquid organic medium at a temperature of from to 100C.

8. A process in claim 7 where the reaction is conducted in an aprotic solvent medium.

9. A process as defined in claim 7 wherein R and R are taken together with the nitrogen to which they are bonded to complete a succinimido or phthalimido group; R is a C to C -alkyl, p-nitrobenzyl, pmethoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2- trichloroethyl, phenacyl or p-halophenacyl where halo denotes chlorine or bromine; and each of X and Y is chlorine, and the reagent is zinc in acetic acid.

10. A process for preparing penicillins having a natural steric configuration which comprises treating a compound of the formula COOK-3 0 El S C CH3 N 1 Y wherein R taken alone, denotes an acyl group of the formula R -cH -CO- where R,, is

ii C CH where each of R and R is hydrogen or a halogen (fluorine, chlorine, bromine or iodine); or R and R taken together with the nitrogen to which they are bonded complete a succinimido or phthalimido group, R is hydrogen, C to C -alkyl, p-nitrobenzyl, p-methozybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2-trichloroethyl, trimethylsilyl, phenacyl, or p-halophenacyl where halo denotes chlorine or bromine; X is chlorine or bromine, and Y is chlorine, bromine, hydrogen or -SCN, with a reagent selected from the group consisting of a. zinc in acetic acid, or b. stannous chloride in a liquid protic organic medium at a temperature of from about 0 to [00C.

UNITED STATES PATENT'AND, TRADEMARK'OFFICE 7 CERTIFICATE OF CORRECTION PATENT N0. ,89T, i +5 I DATED July 29, 1975 INVENTOR(S) I Stjepan Kukolja It is certified that error appears in the above-identified'patent and that said Letters Patent are hereby corrected as shown below:

Page 1 of 2 Column 15, line 50, the structure it claiml should be as follows:

Column 16,-linef25, the first structure in claim 7 should read as follows:

UNITED sTATEs PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION,

Q PATENT NO. 3,897,hh5

DATED July 29, 1975 Page 2 of 2 |NV ENTOR( I Stjepan Kukolja It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column l7, line 20, the first structure in claim 10 should read as follows:

- O N/\, CH3 s H, s CH8 R 1 \r X Y Column 18, line 1, the structure should reas as follows:

. Q 7 A Signed and Scaled this Sixreen'rh D of August 1977 [SEAL] Attest:

RUTHC. MASON c. MARSHALL DANN Attes'mg ff Commissioner of Patents and Trademarks 

1. A 5-EPI-PENICILLIN COMPOUND OF THE FORMULA
 2. A compound as defined in claim 1 wherein R1 and R2 are taken together with the nitrogen to which they are bonded to complete a succinimido or phthalimido group, and R3 is a C1 to C4-alkyl, p-nitrobenzyl, p-methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2-trichloroethyl, trimethylsilyl, phenacyl, or p-halophenacyl where halo denotes chlorine or bromine.
 3. A compound as defined in claim 2 wherein R3 is 2,2,2-trichloroethyl.
 4. A compound as defined in claim 2 wherein R3 is benzhydryl.
 5. A compound as defined in claim 2 wherein R3 is C1 to C4-alkyl.
 6. A compound as defined in claim 1 wherein R1 and R2 taken together with the nitrogen to which they are bonded complete a succinimido or phthalimido group and R3 is hydrogen.
 7. A process for preparing a 5-epi-penicillin which comprises treating a compound of the formula
 8. A process in claim 7 where the reaction is conducted in an aprotic solvent medium.
 9. A process as defined in claim 7 wherein R1 and R2 are taken together with the nitrogen to which they are bonded to complete a succinimido or phthalimido group; R3 is a C1 to C4-alkyl, p-nitrobenzyl, p-methoxybenzyl, benzyl, benzhydryl, phthalimidomethyl, succinimidomethyl, 2,2,2-trichloroethyl, phenacyl or p-halophenacyl where halo denotes chlorine or bromine; and each of X and Y is chlorine, and the reagent is zinc in acetic acid.
 10. A process for preparing penicillins having a natural steric configuration which comprises treating a compound of the formula 